
using System;
using System.IO;
using System.Security.Cryptography;

namespace stefc.geo.lib
{

	/// <summary>
	/// encrypt and decrypt strings
	/// </summary>
	public static class Encryption
	{
	    /// <summary>
	    /// Encrypts the string.
	    /// </summary>
	    /// <param name="clearText">The clear text.</param>
	    /// <param name="Key">The key.</param>
	    /// <param name="IV">The IV.</param>
	    /// <returns></returns>
	    private static byte[] EncryptString(byte[] clearText, byte[] Key, byte[] IV)
	    {
	        MemoryStream ms = new MemoryStream();
	        Rijndael alg = Rijndael.Create();
	        alg.Key = Key;
	        alg.IV = IV;
	        CryptoStream cs = new CryptoStream(ms, alg.CreateEncryptor(), CryptoStreamMode.Write);
	        cs.Write(clearText, 0, clearText.Length);
	        cs.Close();
	        byte[] encryptedData = ms.ToArray();
	        return encryptedData;
	    }
	
	    /// <summary>
	    /// Encrypts the string.
	    /// </summary>
	    /// <param name="clearText">The clear text.</param>
	    /// <param name="Password">The password.</param>
	    /// <returns></returns>
	    public static string EncryptString(string clearText, string Password)
	    {
	        byte[] clearBytes = System.Text.Encoding.Unicode.GetBytes(clearText);
	        PasswordDeriveBytes pdb = new PasswordDeriveBytes(Password, new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
	        byte[] encryptedData = EncryptString(clearBytes, pdb.GetBytes(32), pdb.GetBytes(16));
	        return Convert.ToBase64String(encryptedData);
	    }
	
	    /// <summary>
	    /// Decrypts the string.
	    /// </summary>
	    /// <param name="cipherData">The cipher data.</param>
	    /// <param name="Key">The key.</param>
	    /// <param name="IV">The IV.</param>
	    /// <returns></returns>
	    private static byte[] DecryptString(byte[] cipherData, byte[] Key, byte[] IV)
	    {
	        MemoryStream ms = new MemoryStream();
	        Rijndael alg = Rijndael.Create();
	        alg.Key = Key;
	        alg.IV = IV;
	        CryptoStream cs = new CryptoStream(ms, alg.CreateDecryptor(), CryptoStreamMode.Write);
	        cs.Write(cipherData, 0, cipherData.Length);
	        cs.Close();
	        byte[] decryptedData = ms.ToArray();
	        return decryptedData;
	    }
	
	    /// <summary>
	    /// Decrypts the string.
	    /// </summary>
	    /// <param name="cipherText">The cipher text.</param>
	    /// <param name="Password">The password.</param>
	    /// <returns></returns>
	    public static string DecryptString(string cipherText, string Password)
	    {
	        byte[] cipherBytes = Convert.FromBase64String(cipherText);
	        PasswordDeriveBytes pdb = new PasswordDeriveBytes(Password, new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
	        byte[] decryptedData = DecryptString(cipherBytes, pdb.GetBytes(32), pdb.GetBytes(16));
	        return System.Text.Encoding.Unicode.GetString(decryptedData);
	    }
	}
}

